1. Field of the Invention
The present invention relates to a frame, and more particularly to a frame for a bicycle that has a shock absorber to provide smooth operation.
2. Description of Related Art
With reference to FIGS. 5 and 6, a conventional bicycle frame with a shock absorbing capability has a front frame (91), a rear frame (94, 94′) and a shock absorber (90A, 90B). The front frame (91) has a mounting bracket (92) and a driving bracket (93, 93′). The mounting bracket (92) is attached solidly to the front frame (91). The driving bracket (93, 93′) is attached pivotally to the front frame (91) and has a front end and a rear end. The rear frame (94, 94′) is connected pivotally to the front frame (91) and the rear end of the driving bracket (93, 93′) and move ups and pivots the driving bracket (93, 93′) when a shock is transmitted to the rear frame (94, 94′). The front end of the driving bracket (93, 93′) protrudes into the front frame (91). The shock absorber (90A, 90B) is mounted pivotally between the mounting bracket (92) and the front end of the driving bracket (93, 93′) and absorbs any shock transmitted to the driving bracket (93, 93′) from the rear frame (94, 94′).
However, the conventional bicycle frame has the following shortcomings.
1. When the driving bracket (93) in one embodiment of the conventional bicycle frame presses the shock absorber (90A), the shock absorber (90A) is subjected to an angular displacement of up to about 5.67°. In another embodiment of the conventional bicycle frame, the shock absorber (90B) is subjected to an angular displacement of up to about 9.94°.
2. The angular displacement of the shock absorber (90A, 90B) produces lateral friction in the shock absorber (90A, 90B), which causes the shock absorber (90A, 90B) to wear unevenly and eventually fail. Even slight uneven wear of the shock absorber (90A, 90B) can adversely influence the effectiveness of the shock absorber (90A, 90B) and reduce the smoothness and comfort of the conventional bicycle frame.